With the recent advances in manufacturing of integrated circuits, it is now common that electronic products, such as mobile phones and home appliances, incorporate integrated circuit packages having high-performance CPUs and large-capacity memories.
The size of an integrated circuit or package is determined by the number of input and output terminals for exchanging electronic signals between the integrated circuit and an external device. An increase in the number of I/O terminals will cause disadvantages, such as an increase in circuit area and in cost. Especially in the case of integrated circuits for incorporation into compact electronic products such as mobile phones, the smaller circuit area is desirable. Consequently, the number of I/O terminals needs to be limited.
Further, some recently available integrated circuit packages include a debugging circuit for debugging errors of the integrated circuit. Such a debugging circuit is capable of monitoring signals on the bus and outputting the signals to the outside of the integrated circuit.
Patent Document 1 describes an analyzing device that causes the internal state of an integrated circuit to be output to the outside and analyzed. More specifically, the analyzing device performs a monitoring phase and an I/O phase by the time sharing. In the monitoring phase, the internal state of the integrated circuit is output to the outside via one or more predetermined terminals. In the I/O phase, electronic signals are input from and output to the outside via each predetermined terminal.